Roller align drive

ABSTRACT

A mounting is disclosed imparting several degrees of freedom to fixed or semi-fixed drive units which maintains coplanar relationship between a drive sprocket or sheave and a driven sprocket or sheave and overcomes the tendency of the drive chain or belt to become detached or subject to extreme wear under the influence of displacement forces acting on their spaced axes. In one embodiment the mounting includes a traversing radial torque anchor in combination with a radial follower arm to support the drive member axis parallel to the axis of the driven member and to maintain the drive axis in a relatively fixed circumferential position to the driven axis. The follower arm has a roller intermediate its ends which rolls against the side of the driven member under bias and the extended end is pivoted to the journal holding the drive member in its drive position. Other embodiments are disclosed.

United States Patent [191 Miller Feb. 13, 1973 ROLLER ALIGN DRIVE [76]Inventor: Eugene J. Miller, 3912 W. Oak St.,

McHenry, Ill.

[22] Filed: Sept. 20, 1971 [21] App]. No.: 181,770

UNITED STATES PATENTS 2,599,852 6/1952 McClain ..259/l77 R 2,944,7997/1960 Larson ..259/l77 R 3,136,165 6/1964 Pitts ..259/177 R PrimaryExaminerWilliam 1. Price Assistant Examiner-Stuart S. LevyAttorney-Watson D. Harbaugh et al.

[5 7 ABSTRACT A mounting is disclosed imparting several degrees offreedom to fixed or semi-fixed drive units which maintains coplanarrelationship between a drive sprocket or sheave and a driven sprocket orsheave and overcomes the tendency of the drive chain or belt to becomedetached or subject to extreme wear under the influence of displacementforces acting on their spaced axes. in one embodiment the mountingincludes a traversing radial torque anchor in combination with a radialfollower arm to support the drive member axis parallel to the axis ofthe driven member and to maintain the drive axis in a relatively fixedcircumferential position to the driven axis. The follower arm has aroller intermediate its ends which rolls against the side of the drivenmember under bias and the extended end is pivoted to the journal holdingthe drive member in its drive position. Other embodiments are disclosed.

18 Claims, 6 Drawing Figures PATENTED FEB I 3l973 SHEET 10F 3 INVENTOR.EUGENE ll M/L LER any rfimu I Arrorn eys PAIENTEDFEB] 3:913 3,716,219

sum 3 or 3 I/VVEIVTOR: EUGENE d MILLER By YM A Horneys ROLLER ALIGNDRIVE BACKGROUND OF THE INVENTION The problem of maintaining a drivesprocket in proper alignment with a driven sprocket is not acute in theordinary installation where both the prime mover and the member to bedriven are stationary or no other displacement forces act on the units.However, there are installations wherein exterior forces causemisalignment of the drive and driven sprockets wherein increased wear ofthese parts is experienced and difficulty is experienced in keeping thedrive chain on the sprockets. A typical example comprises the chaindrive units used on concrete ready-mix trucks wherein the prime moverrotates the heavy mixer drum carried on fore and aft bearing supportsattached and supported on an angle to the horizontal plane of the frameof the vehicle. The mixer drums are also subjected to fore and aftmoments of force due to braking and acceleration of the truck.

In this art, the mounting elements for the auxiliary drive connectionbetween the truck frame and the mixing drum are fixed, or semifixed. Thefixed mountings cannot be used for large trucks where the axis ofrotation of the concrete drum has any tendency to shift in relation tothe drive axis and are generally confined to use on smaller mixer trucksor small trailer mounted concrete mixers. The semi-fixed units aremounted for easy detachment for repair, are locked in place during useand no allowance for misalignment is provided. Any freedom of movementis lost by the locking and does not compensate for misalignment due tostresses on the parts or keep the roller chain on or aligned with thedrive sprockets during all conditions of use.

Only such adjustments are provided by the prior art devices as arenecessary to initially adjust and align the drive and driven sprocketsat the time of installation, and to thereafter make adjustments for wearof the working parts or for easy disassembly for replacement, etc.Little or no attention is paid to the influence of displacement forces,such as the twisting of the frame of the vehicle as it negotiates uneventerrain. Only limited play or freedom of movement between the drive axisand the driven axis can and is obtained through the inherent loosenessof bevel gearing, bearings and the chain drives that are used. Vibrationdampening systems are employed with spring-mounted orgyroscope-controlled drive units where work under high speeds and lowtorque is performed. These systems are totally inadequate, too expensiveand cannot be used under the extremely severe work conditions of theconstruction field. The problem of maintaining proper alignment of thedrive and driven axes of heavy construction equipment is accentuated bythe necessity of increased pay loads per vehicle and the need foroff-the-road capability at many construction locations. Although theproblem is not as severe in the sheave art where belt drives are used,misalignment can cause excessive wear and squeaking which are overcomeby the use of the drive unit suspension of this invention. Those endlessdrive belt units wherein the belt has cleats to mesh with depressions inthe sheave can benefit by the use of this invention.

SUMMARY OF THE INVENTION This invention primarily concerns a suspensionfor chain drive units that provides the degrees of freedom of movementfor the drive sprocket necessary to keep it in the plane of the drivensprocket so that the chain therebetween does not come off of thesprockets under the influence of exterior torque forces acting on theaxis of either sprocket. More particularly, the suspension maintains thedrive axis and the driven axis in the same plane and at a constantradial distance from each other as the driven axis is subjected tocircular displacement at an end spaced from the driven member and alsosubjected to axial displacement in relation to the drive axis. Statedotherwise, the drive axis of a power take-off unit and the axis of thepart being driven are normally perpendicular to the same plane, that inwhich the drive sprocket or sheave and the driven sprocket or sheave arerotating. The rotational axis of the driven member, with one fixedbearing support is subject to external forces which displace or off-setthe plane of rotation of the driven member from that of the drivemember. As this occurs, the suspension for the drive member of thisinvention allows or forces the drive member to constantly orient itselfso that its plane of rotation always lies in the displaced plane ofrotation of the driven member.

The suspension includes a multiple pivot linkage frame mounting for thedrive member, and its powertake-off unit, for constant followingmovement with the changing plane of rotation of the driven member, underthe control of an adjustable radial follower arm affixed between thesupporting frame and the drive member or carried by the drive member,and pivoted or held in a plane normal to the combined planes of thedrive and driven members which maintains the members in a substantiallycoplanar and fixed radial as well as circumferential relationship, andan adjustable traversing swivel means or linkage which torsionallyanchors the drive member tangentially within and following the coplanarrelationship thus established. The drive member is accordingly held bythe suspension so that it is able to follow or remain in the plane ofthe driven sprocket as the axis of the latter shifts with the torsionaland longitudinal forces absorbed by the frame of the truck or otherstructure. Although the invention will be illustrated in the drawings byreference to the component parts of a ready-mix truck, it is apparent toone skilled in the art that the suspension of this invention can be usedin other applications where greater than normal torsional and thrustforces are applied to frame mounting for either the driven or drivemember, whether connected by a chain or belt drive.

As used in this specification and claims, the term drive unit is meantto include any means having a rotatable drive member which is adapted tobe used to rotate a driven member that is supported on a frame or otherstructure which is subject to displacement forces. The source of powerfor the drive unit can be a power take-off shaft, an electrical motor ora hydraulic motor as long as rotational power is applied to the drivemember.

By flexible means is meant any means encompassing the periphery of thedrive and driven members such as flat belts, V-belts, a series of belts,cleated belts, roller chains, silent chains and ropes to rotate them inunison. The suspension of this invention can be applied to power ordrive units wherein the drive shaft is at any angle, that is, the driveshaft can be vertically oriented as well as the driven shaft. The drivesystem in which the suspension is used can be any pair of sheaves,pulleys or sprockets whose axes of rotation tend to move out of theproper orientation for effective operation regardless of how many othersuch driven, idler or loose pulleys may be in the system.

The axis of the drive member is essentially parallel to and radiallyspaced from the axis of the driven member, but can be located at anydesired circumferential relationship therewith. The drive unit of thisinvention can be used for any frame-supported rotatable work or drivenmember wherein one or the other of its supporting journals or bearingsis subjected to displacement. On a ready-mix truck both the drive axisand the driven axis may be canted in relation to the plane of the truckframe or be at an angle fore and aft of the frame.

DESCRIPTION OF THE DRAWINGS The torque absorbing suspension drive unitof this invention is further illustrated by the drawings wherein:

FIG. 1 is a fragmentary perspective view showing the general arrangementof the suspension for the drive unit of this invention as applied to aready-mix truck and also illustrating the twin roller bearing mount usedfor the rear end of mixer drum;

FIG. 2 is a fragmentary perspective view of the suspension unit withparts cut away to show the details of the mounting;

FIG. 3 is a fragmentary top plan view taken along the lines 3-3 of FIG.1 in the combined planes of the drive and driven members and at an angleto the plane of the frame;

FIG. 4 is a fragmentary side view of the suspension taken from the pointof view of lines 44 of FIG. 3;

FIG. 5 is a fragmentary view of the aft end of the reduction gearhousing to illustrate one form of pivotal linkage mount therefor; and

FIG. 6 is a partially diagrammatic perspective view of the assembly toshow the degrees of freedom that are provided.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings inwhich the reference characters designate like parts, there is shown areadymix truck 10 which incorporates a power take-off unit or drive unithaving the suspension of the present invention. The truck 10 comprisesthe cab 12 supported on the frame 14 having the longitudinal sidemembers 16 and 18, with suitable transverse front and rear cross members(not illustrated), to support the cab and carry the tired wheels, onlyone of which is illustrated at 20, and provide steering and motive powerfor the truck as is known in the art. The truck frame includes therigidifying box frame 22 affixed between the side members 16 and 18,just behind the cab 12 with the spaced stanchions 24 and 26 supporting awater tank 28 used for the purpose of supplying water to wash theequipment free of fresh concrete. Other auxiliary equipment such asaccumulator 30 for the air brakes, the oil supply tank 32 for thehydraulic system and the battery box 34, is carried by the frame behindthe cab.

The box frame 22 has the front bearing support members 36 and 38 (FIG.3) which can be any desired rigid construction, carried along the centerline of the frame, to hold the bearing 40 of the stub shaft or axis 42rotatably supporting the forward end of the mixer drum 44. A similarcross frame member, and roller supports 45 as provided at the rear ofthe frame, with the pair of rollers 46 suitably mounted at their upperends and positioned transversely of the frame 16. This tapered end ofthe mixer drum carries the circumferential track 47 and is provided witha flanged opening 48 allow passage of concrete as desired. The tracksurface 49 is beveled so that the rollers 46 have their axessubstantially parallel to the frame 16 and so spaced as to rotatablysupport the rear end of the mixer drum 44 on a longitudinal axis abovethe frame and higher at the rear than at the front. Various forms ofspaced roller supports 46 are provided for the mixer drums of ready-mixtrucks and the longitudinal axis about which the mixer drum rotates isthereby elevated above the front support and at an angle of about 20 to25 to the plane of the frame. Provision is made for an opening in therear end wall of the mixer drum to admit the concrete or its ingredientsin loading the truck and to discharge the concrete at the job site.Chutes and conveyors may also be used at the rear end 48 of the mixerdrum 44 to aid in discharging the concrete to a desired location. A topcenter hold-down roller (not shown) can be provided. Accordingly, therear bearing or roller is a cradle of rather large diameter necessitatedby the flanged opening 48. Rear spaced roller bearing supports of thistype are particularly subject to torsional displacement and fore and aftshifting of the drum 44.

In any event, the mixer drum 44 is rotatably supported by rigid frontand non-rigid rear bearing supports above the frame 14 in a manner to beinfluenced by the torsional action of the frame as the wheels 20negotiate deviations in the grade whether within or beyond the limits ofmovement of the trucks spring system, front and rear of the frame. Thesetorsional shifting forces are ever present in a truck of this nature andare magnified by the size (length and capacity) and weight of the mixerdrum requiring a longer frame. Furthermore, trucks, such as this arecalled upon to negotiate any terrain over which the driver can possiblymake it travel, often to the detriment of the auxiliary power drive forthe mixing drum.

In order to thoroughly mix and also dispense the contents of the mixerdrum 44, means are provided to continuously rotate the drum as ittransports the concrete and delivers same to the required location. Suchmeans include an auxiliary take-off drive shaft 50 (FIG. 3) which isconnected by suitable universal joints and gearing to the transmissionof the truck and individually controlled by the operator through a shiftlever and clutch located either in the cab or behind the cab, asdesired. The power take-off shaft 50 connects to a suitable drivesprocket or gear within the transfer case 52, the end bearing housing ofwhich is illustrated at 54. Suitable reinforcing members 55 for thepower take-off are provided, affixed to the truck frame member 16, whichis located so as to be convenient for servicing and also at the desiredspaced relationship from the axis 42 of the mixer drum. The transfercase 52 contains a larger gear or sprocket, the bearing or axis housingof which is illustrated at 56, connected to the power unit (reductiongear) housing 58 as the final power take-off through the primary driveshaft or drive axis 60 carrying the drive member or sprocket 62.

The box frame 64, having a pair of side members 66 and 68 and a basemember 70, affixed to the side frame member 16, extends outwardly fromthe truck to provide a rigid support under the transfer case 52 andpower unit housing 58 which latter are unified and completely enclosedto protect the-working parts.

As one embodiment of this invention, a pair of link members 74 and 76 isprovided and supported in spaced pivotal relationship from the inside ofthe box frame 64. The lower ends of each link have a suitable bore holeto receive the pivot pin 78 therebetween and fit across correspondingaligned bore holes in the correspondingly spaced support members 64 and70. Suitable bearing bushings and the like can be used so that eitherthe links rotate upon the pin 78, the pin rotates in the members 64 and70 or both of these rotational relationships attain. The links 74 and 76are cross-braced and held in coplanar relationship by the rod 80 and thesleeve 81 which encompasses the pin 78 and suitable nuts 82 at the endsof the pin 78 hold the assembly to the side frame support represented bythe numeral 64. FIG. 5 is an end view of this pivot assembly.

The housing 58, providing power to the drive shaft 60 and the drivesprocket 62, has a pair of oppositely facing bosses 84 and 86 receivingthe axially-aligned stub shafts 88 and 90, respectively. Alternatively,the shafts 88 and 90 can be one continuous shaft through the housing.The upper ends of the links 74 and 76 are rotatably mounted to thesespaced shafts and held in place by the nuts illustrated at 92. The innerlinkage 76 is provided with the inwardly extending tab 94 while thestationary bracket 96, affixed to or a part of the frame assembly, has acorresponding upright tab 97 mounted to the rear of the linkage 74-76 inrelation to the frame 16. Each tab has a bore hole or other suitablemeans to receive the ends of the tension spring 98 biasing the housing58 to the rear about the linkages 74-76. The housing can, accordingly,pivot toward and away from the rear of the frame on the pin 78 and alsopivot upwardly or downwardly on the pins 86-88. The junctures of thebosses 84 and 86 and the tube 81 with the inside of the links andjunctures of the outsides of the links with the support 64 are of closetolerance to provide little or no side play.

At the rear end of the housing 58 adjacent the drive sprocket 62 thereis provided the lobed flange or journal 100 affixed to or part of thehousing. The outer lobe carries the bifurcated yoke member 102 and theinner lobe carries the flat tab portion 104. Although the lobed flange100 is shown to be substantially symmetrical about the end of thehousing with the yoke 102 and the tab 104 diametrically opposite eachother, this arrangement is by no means critical to the functioning ofthe part as will become apparent as this description proceeds. The yoke102 has the spaced tabs 106 and 108 with suitable aligned bores carryingthe pivot pin 1 l0 therebetween in spaced relationship from the body ofthe yoke member.

The side frame member 16 carries the bracket member 112 immediatelybelow the rear end of the housing 58 under the journal 100, with theoutwardly extending yoke member 114 attached thereto which includes thespaced tabs 116 and 118 having aligned bores to receive the pivot pin120. The rod or torque anchor member 122, comprising adjustabletelescoping members affixed by the locking ring 124 is attached betweenthe pivot pins and 120 by means of the ball swivel mounts at each end.The rod member 122 and the ball swivel mounts 130 at each end, connectedbetween the frame and the rear end of the housing 58, comprise theradial torque member of this invention. Each end of the rod member 122can rotate about the axis of the respective pins 1 10 and 120 and isalso free to pivot into and out of its normal generally perpendicularrelationship with each pin. This imparts a double pivot action at theends of the rod and a wrist or gibble-mount action, in addition, withonly the lower end being restricted in that the axis represented by thepin 120 is fixed in relation to the frame.

The upper end of the rod or radial torque member 122 is thus capable ofmovement in circles of varying diameter, the centers of which areessentially a fixed, but adjustable radius or distance from the lowerend. As shown in FIG. 4, the universal or gimbal mounting is partiallyillustrated by the ball portions 132, as integral parts of each of thepins 110 and 120 which serve as lateral or twist bearing surfaces forthe encompassing mountings 130. The illustrated swivel 130 can be of thetype manufactured by New Departure Bearing Co. The lock nut 124 uponbeing loosened, allows the mounts 130 to be extended or retracted to thedesired length and then tightened to lock the rod 122 to that position.

The front wall 134 of the mixer drum has the reinforcing housing 136 towhich is attached and carried the large driven sprocket or ring gear 138encompassed by the drive chain 140. The assembly is arranged so that thelarge driven sprocket 138 and the drive sprocket 62 are essentially incoplanar aligned relationship and their rotational axes are laterallyspaced and essentially parallel to each other, with the axis 60 beingadjustable in relation to the axis 42 to allow the drive chain 140 to bereceived upon the respective teeth 142 and 144 in drive relationship.Accordingly, power input from the take-off shaft 50 is transmittedthrough the off-set drive connection in the transfer case or housing 52,to the reduction gear or transmission drive unit 58 and to the driveaxis on shaft 60 for rotation of the mixer drum 44 in any desireddirection indicated by the arrow 146. The sprocket sizes are chosen sothat the mixer drum is rotated at about 1 to 18 rpm-during the transportand unloading of concrete. During unloading of concrete the direction ofrotation of the drum 44 is reversed, and this action, coupled with theresulting load displacement also causes mis-alignment of the drivesprocket which is overcome by this invention.

Referring back to the lobed flange-journal 100 and its inner tab 104, itis seen that the roller or radial alignment rod member comprising theouter octagonal housing 152 in threaded engagement upon the inner rod154, is affixed or linked thereto by means of the yoke member 156 andthe pivot pin 158 extending through suitable aligned bores. The otherend of the roller alignment member 150 has the flattened end portion 160received within the fixed bracket 162 by means of the pivot pin 164carried by the fixed support 166 which is part of the structureconstituting the support for the front end of the mixer drum 44.

As shown in FIG. 3, the upper pivot pin 164 is at or near the center ofthe axis 42 of the mixer drum and radially aligned with and above theaxis 60 of the drive gear 62. The lower pivot pin 158 is located on aline between the axis 42 and the axis 60. Between the ends of the rolleralignment rod member 150, and preferably near the outer periphery of thedriven sprocket 138, there is provided the vertical alignment roller 168carried on the larger diameter rod portion 155 by the bearing mount 170.The roller 168 can be constructed of rubber or tough plastic, for sometypes of equipment, although a tough metal roller is used for concretetrucks. The periphery thereof is beveled to be in the plane of thedriven sprocket 138. It is seen that the spring 98 urges the housing 58and the drive sprocket 62 to the rear or axially in relation to thedriven sprocket 138 and forces the roller 168 against the outer flatsurface 172 of the driven sprocket 138.

Although the roller 168 can be located anywhere along the length of thealignment member 150 it is preferably located outwardly of the axis 42as far as possible so that the response of the device does not placeundue strain on the parts and the proper mechanical advantage isimparted to the linkage. By placing the roller 168 as near as possibleto the drive sprocket 62, the effective length of the lever indicated bythe rod portion 155 therebetween is shortened and the response tochanges in the plane of rotation of the driven sprocket 138 is increasedso the drive sprocket tracks at all times with the chain 140 coming offthe driven sprocket and alternatively the driven sprocket tracks at alltimes with the chain as it comes off the drive sprocket. In chain driveconnections the chain leaves the teeth (comes off) at those positionswhere it first engages either the driven or drive sprockets and notthose portions where it is disengaging. Any misalignment of the chaincauses undue wear, noise and ultimate damage to the working parts.

In the embodiment so far described, means are provided to allow thedrive unit 58 and its drive sprocket 62 to move in exact and constantlyaligning relationship with any twisting action the frame may have uponthe driven sprocket 138 so that the chain 140 does not come off eithersprocket. The system is capable of maintaining correct alignment evenwith the extreme twisting of the frame. These functions are illustratedin FIG. 6. p

The vertical arms or links 74-76 allow fore and aft swing of the driveunit 58 along the are indicated by the arrow 180. The arrow 182indicates the slight vertical component of pivot motion of the driveunit about the axis 88-90 at the ends of these links under the controlof the torque anchor 122, while the arrow 184 represents the radialcontrol component of movement imparted by the roller arm 150 as theroller 168 maintains the drive unit in alignment with the driven memberand carries the load of the drive unit under the bias of the spring 98.As the mixing drum rotates the roller 168 rides or rotates upon thecircumferential bearing surface 172, provided on the front side of thedriven sprocket 138 or alternatively by the flat end of the mixer drum.The traversing radial torque anchor 122, with its ball swivel mounting,is tied or linked as an extension of the roller arm 150 to allow thesedegrees of freedom to coexist in harmony as represented by the circulararrow 186.

Accordingly, the plane of the drive sprocket 62 is constantly maintainedcoincident with the plane of the driven sprocket 138 as shown by thein-line relationship of FIG. 3. If this relationship is upset by atwisting of the frame, bouncing of the mixer drum, changes in torque onthe drive units or sudden application of the vehicle brakes, asindicated by the broken line A-B in FIG. 3, the mounting allows thedrive sprocket 62 to move to the rear (in this instance) and turnslightly at the pivots 158 and swivels 130. The restraint of both theroller 168 and the anchor 122 cause the drive sprocket to come withinthe plane represented by the line A-B. The roller arm 150 is also usedto adjust the tightness of the chain 140 about the sprockets to thespecified amount. The traversing torque anchor 122 yields to theseadjustments.

in effect, the drive sprocket 62 is journaled in a floating linkagewhich can pivot up and down and fore and aft and are axially off-setfrom each other. This floating linkage is maintained at a fixed radiusfrom the center of the driven sprocket 138 and given a swivel action atits outer end; all biased toward the driven sprocket by the spring 98.It is to be observed that the axes of the pins 158 and 164 are normal tothe longitudinal axis of the radial arm 150 and allow the radial arm topivot in a plane which includes the longitudinal axes of both the driveshaft 60 and the driven shaft 42. Also, the roller arm 150 (see FIG. 3)and the flange journal do not lie in a common plane, although the flange100 and the torque anchor 122 have their longitudinal axes substantiallyco-planar. This arrangement places the thrust of the roller arm as closeas possible to the drive sprocket 62 making the unsupported length ofthe drive shaft 60 as short as possible and places less strain on thebearing injournal flange 100.

Referring to FIG. 4, it is seen that the longitudinal axis of the torqueanchor 122 is off-set from the plane of the chain drive in one positionof the parts, and is not perpendicular to the drive axis 60, its pivotpins and being parallel are oriented fore and aft with the frame 16.This is a compromise position to allow the greatest pivoting action atthe torque anchor to accommodate the twist of the frame and fore and aftmovement of the drive unit 58 and different drive shaft angles inrelation to the frame. The torque anchor 122 should be as long aspossible and the longitudinal axis of 122 is always inside the plane ofthe driven member in relation to the vertical inclination of thesprocket 138 in relation to the truck frame 16.

It is apparent from the foregoing description that the invention is notto be limited to the particular orientation of the parts shown in thedrawings. The journal 100 can be on the other or rear side of the drivesprocket 62 and the axis 42 of the mixer drum can extend forwardlyinstead of rearwardly of the frame support 16-18. The relative sizes ofthe drive and driven sprockets is immaterial to the proper functioningof the parts and instead of a speed reduction a speed increase can beattained with the drive sprocket larger than the driven sprocket. Thepin 164 is preferably in line with and intersecting the axis of rotation42 of the working member.

Similarly, the pivots or links 74-76 need not be under and supportingthe housing 58 for the drive unit and these linkages can be locatedabove the housing so that it hangs from the linkages. Although a pair oflinkages is shown, one of them can be eliminated i.e., a single linkageof proper strength and suitably journaled will serve the same purpose.Also, the torque arm 122 can be reversed with the lower yoke member 114above the yoke member 102, that is in a position 180 from that shown.

The unit will function properly without the spring 98 because the chain140 is in guided relationship upon the teeth of the sprockets when underthe driving load of rotating the drum 44. However, when the drive unitis slack or coasting and the brakes are applied the spring 98 preventsthe drive unit 58, which is fairly heavy, from pivoting forward suddenlyand causing the chain to walk off of the teeth. Alternatively, theroller arm 150 can be replaced by a stout stub shaft made integral withthe journal 100 and extending radially toward the front bearing 42 withthe roller 168 at the extended end for engagement with the surface 172or the flat end of the mixer drum, provided an alternate means such as aturn-buckle is used to pull the journal 100 away from the axis 42 tomaintain the chain or belt drive in taut condition. It is also apparentthat the torque anchor 122 is preferably of sufficient length that thecurvature of swing of the upper end does not interfere with thefollowing action of the drive unit 58. The drive and driven members canbe reversed, that is, the housing 58 can represent the driven member andthe mixer drum 44 can represent the drive member for other applicationsof the invention.

Accordingly, this invention provides a drive unit for a drive member anda frame-supported driven member connected therebetween by anencompassing endless flexible member, the axesof which are subject totorsional disturbances. The unit includes housing means journaling thedrive means along the drive axis in radially spaced substantiallyco-planar relationship from and operatively connected to the drivenmember by the flexible endless member. Also included are the pivotalsupport means for the housing for axial and angular movement of thedrive axis along the driven axis, the radially oriented arm means tomaintain the spaced relationship of the drive and driven axes, theanchor means so connected to allow a circular moment of freedom to thehousing means which traverses the plane of said drive and driven axesand the roller means carried by the roller arm biased against asubstantially flat end portion of said driven means which rotatestherewith as a part or extension thereof in a plane substantiallyperpendicular to the driven axes.

What is claimed is:

l. A drive unit for a drive member and a frame-supported rotatabledriven member connected by an encompassing endless flexible member, therespective drive and driven axes of which are subject to torsionaldisturbances, comprising:

means housing and journaling said rotatable drive member along saiddrive axis in radially spaced substantially co-planar relationship fromand operatively connected to said rotatable driven member throughcircumferential engagement with said flexible member;

said driven member having a flat side surface rotatable in a planesubstantially perpendicular to said driven axis;

means pivotally supporting said housing means from said frame supportfor axial and angular movement of the drive axis along the driven axis;

radially oriented arm means pivotally connected for movementsubstantially in the plane of said drive and driven axes with one endthereof connected to said frame support and the other end connected toan inner side of said housing means to maintain said radially spacedrelationship of said drive and driven axes;

anchor means universally connected at one end to an outer side of saidhousing means and at the other end to said frame support allowing acircular moment of freedom to said housing means traversing the plane ofsaid drive and driven axes;

roller means intermediate the ends of said arms means for rotationalcontact with said side of said driven member; and

means biasing said housing means and drive member about said pivotalsupport with said roller means in idling rotational contact with theside of said driven member whereby the planes of rotation of said driveand driven members are maintained coincident during torsionaldisplacement therebetween.

2. A drive unit in accordance with claim 1 in which:

said rotatable drive member and said rotatable driven member aresprockets and said endless flexible member is a roller chain.

3. A drive unit in accordance with claim 1 in which:

said rotatable drive member and said rotatable driven member are sheavesand said endless flexible member is a belt.

4. A drive unit in accordance with claim 1 in which:

said means pivotally supporting said housing means comprises a linkagepivoted at one end to said frame support and pivoted at the other end tosaid housing means.

5. A drive unit in accordance with claim 1 in which:

said radially oriented arm means is connected to said frame supportsubstantially coincident with the center of rotation of said drivenmeans.

6. A drive unit in accordance'with claim 1 in which:

said radially oriented arm means is connected to said frame support onan axis substantially perpendicular to the plane of said drive anddriven axes.

7. A drive unit in accordance with claim 1 in which:

said housing means includes a journal rotatably supporting said drivemeans;

the inner sides of said journal carrying said radially oriented armmeans includes a pivot mount therefor and the outer side of said journalincludes a swivel mount for said anchor means, the longitudinal axis ofwhich is spaced from said drive axis and at an angle to the plane ofrotation of said driven member.

8. A drive unit in accordance with claim 7 in which:

said anchor means is suspended between said frame support and saidjournal by means of a swivel mount at each end.

9. A drive unit in accordance with claim 1 in which:

the pivotal connection of said radially oriented arm means with saidframe support is aligned with said driven axis.

10. A drive unit in accordance with claim 1 in which:

said radially oriented arm means includes means to change the effectivelength thereof and adjust tightness of said endless flexible member uponsaid drive and driven members.

11. A drive unit in accordance with claim 1 in which:

said anchor means includes means to change the effective length thereofand adjust the loci of the center of said circular moment of freedom ofsaid housing means.

12. A drive unit in accordance with claim 1 in which:

said drive member is a drive sprocket extending from said housing means,the rotatable driven member is a driven sprocket carrying therewith amixer drum for rotation by means of a drive chain therebetween;

said mixer drum is mounted on a fixed axis at said driven sprocket andan inclined roller axis spaced therefrom;

and said frame support comprises the wheelmounted, elongated frame of aready-mix concrete truck.

13. A drive unit in accordance with claim 12 in which:

the inclined axis of said mixer drum and the axis of said drive sprocketare oriented at an angle to said frame support along its longitudinalaxis and said roller axis comprises a pair of laterally spaced rollerssupported by said frame and engaging the under curved side of said mixerdrum in rolling contact.

14. A mounting for the power take-off-unit of a concrete ready mix truckhaving a mixer drum rotatably mounted on the frame thereof between afront fixed bearing support and an inclined rear roller support, saidpower take-off-unit having a drive sprocket engaging a drive chainoperatively engaging a driven sprocket in co-planar relationship carriedat one of the bearing supports of said mixer drum comprising:

means pivotally supporting said power unit from said frame for axial andangular movement of the drive sprocket along its axis;

radially oriented arm means pivotally mounted for movement substantiallyin the plane of the axes of said sprockets, with one end thereofconnected to said frame substantially central of the axis of said drivensprocket and the other end thereof connected to an inner side of saidpower unit to maintain the radially spaced relationship between saidsprockets;

anchor means universally connected at one end to the outer side of thepower unit and at the other end to said frame allowing a circular momentof freedom to said power unit traversing the coplanar sprockets;

roller means mounted upon said other end of said arm means forrotational idling contact with' the rotating end of said mixer drum; and

means biasing said power unit and drive sprocket about said pivotalsupport with said roller means maintained in said idling rotationalcontact whereby the co-planar relationship of said sprockets ismaintained irres ective of torsional and longitudinal displacemen s ofsaid frame and bearing supports for said mixer drum.

15. A mounting for a power take-off-unit in accordance with claim 14 inwhich:

the means pivotally supporting said unit comprise a pair of linkagespivoted at their respective ends upon vertically spaced paralleltransverse axes, one of which extends substantially centrally of saidunit and the other of which is carried by said frame.

16. A mounting for a power take-off-unit in accordance with claim 14 inwhich:

said radially oriented arm means includes a pair of threadably engagingrod members adapted to be rotated in relation to each other and therebyadjust the tightness of said drive chain about said sprockets.

17. A mounting for a power take-off-unit in accordance with claim 14 inwhich:

said anchor means includes a pair of threadably engaging rod membersadapted to be rotated in relation to each other and thereby adjust theloci of the center of said circular moment of freedom of said unit.

18. In a chain drive unit having a drive sprocket connected to a drivensprocket attached to a mixer drum mounted for rotation on an inclinedaxis upon a readymix truck, the combination of:

linkage means pivotally supporting said chain drive unit for oscillationof said drive sprocket along its rotational axis in a plane fore and aftand parallel to the inclined axis of said mixer drum;

means holding the inner side of said drive unit a fixed radial distancefrom said driven sprocket to tauten said chain drive unit;

a torque anchor holding the outer side of said drive unit in a planetangential to the driven sprocket; and

a roller follower carried by said drive unit and engaging the rotatingend of said mixer drum to maintain the drive sprocket and drivensprocket in following relationship.

I III i

1. A drive unit for a drive member and a frame-supported rotatabledriven member connected by an encompassing endless flexible member, therespective drive and driven axes of which are subject to torsionaldisturbances, comprising: means housing and journaling said rotatabledrive member along said drive axis in radially spaced substantiallyco-planar relationship from and operatively connected to said rotatabledriven member through circumferential engagement with said flexiblemember; said driven member having a flat side surface rotatable in aplane substantially perpendicular to said driven axis; means pivotallysupporting said housing means from said frame support for axial andangular movement of the drive axis along the driven axis; radiallyoriented arm means pivotally connected for movement substantially in theplane of said drive and driven axes with one end thereof connected tosaid frame support and the other end connected to an inner side of saidhousing means to maintain said radially spaced relationship of saiddrive and driven axes; anchor means universally connected at one end toan outer side of said housing means and at the other end to said framesupport allowing a circular moment of freedom to said housing meanstraversing the plane of said drive and driven axes; roller meansintermediate the ends of said arms means for rotational contact withsaid side of said driven member; and means biasing said housing meansand drive member about said pivotal support with said roller means inidling rotational contact with the side of said driven member wherebythe planes of rotation of said drive and driven members are maintainedcoincident during torsional displacement therebetween.
 1. A drive unitfor a drive member and a frame-supported rotatable driven memberconnected by an encompassing endless flexible member, the respectivedrive and driven axes of which are subject to torsional disturbances,comprising: means housing and journaling said rotatable drive memberalong said drive axis in radially spaced substantially co-planarrelationship from and operatively connected to said rotatable drivenmember through circumferential engagement with said flexible member;said driven member having a flat side surface rotatable in a planesubstantially perpendicular to said driven axis; means pivotallysupporting said housing means from said frame support for axial andangular movement of the drive axis along the driven axis; radiallyoriented arm means pivotally connected for movement substantially in theplane of said drive and driven axes with one end thereof connected tosaid frame support and the other end connected to an inner side of saidhousing means to maintain said radially spaced relationship of saiddrive and driven axes; anchor means universally connected at one end toan outer side of said housing means and at the other end to said framesupport allowing a circular moment of freedom to said housing meanstraversing the plane of said drive and driven axes; roller meansintermediate the ends of said arms means for rotational contact withsaid side of said driven member; and means biasing said housing meansand drive member about said pivotal support with said roller means inidling rotational contact with the side of said driven member wherebythe planes of rotation of said drive and driven members are maintainedcoincident during torsional displacement therebetween.
 2. A drive unitin accordance with claim 1 in which: said rotatable drive member andsaid rotatable driven member are sprockets and said endless flexiblemember is a roller chain.
 3. A drive unit in accordance with claim 1 inwhich: said rotatable drive member and said rotatable driven member aresheaves and said endless flexible member is a belt.
 4. A drive unit inaccordance with claim 1 in which: said means pivotally supporting saidhousing means comprises a linkage pivoted at one end to said framesupport and pivoted at the other end to said housing means.
 5. A driveunit in accordance with claim 1 in which: said radially oriented armmeans is connected to said frame support substantially coincident withthe center of rotation of said driven means.
 6. A drive unit inaccordance with claim 1 in which: said radially oriented arm means isconnected to said frame support on an axis substantially perpendicularto the plane of said drive and driven axes.
 7. A drive unit inaccordance with claim 1 in which: said housing means includes a journalrotatably supporting said drive means; the inner sides of said journalcarrying said radially oriented arm means includes a pivot mounttherefor and the outer side of said journal includes a swivel mount forsaid anchor means, the longitudinal axis of which is spaced from saiddrive axis and at an angle to the plane of rotation of said drivenmember.
 8. A drive unit in accordance with claim 7 in which: said anchormeans is suspended between said frame support and said journal by meansof a swivel mount at each end.
 9. A drive unit in accordance with claim1 in which: the pivotal connection of said radially oriented arm meanswith said frame support is aligned with said driven axis.
 10. A driveunit in accordance with claim 1 in which: said radially oriented armmeans includes means to change the effective length thereof and adjusttightness of said endless flexible member upon said drive and drivenmembers.
 11. A drive unit in accordance with claim 1 in which: saidanchor means includes means to change the effective length thereof andadjust the loci of the center of said circular moment of freedom of saidhousing means.
 12. A drive unit in accordance with claim 1 in which:said drive member is a drive sprocket extending from said housing means,the rotatable driven member is a driven sprocket carrying therewith amixer drum for rotation by means of a drive chain therebetween; saidmixer drum is mounted on a fixed axis at said driven sprocket and aninclined roller axis spaced therefrom; and said frame support comprisesthe wheel-mounted, elongated frame of a ready-mix concrete truck.
 13. Adrive unit in accordance with claim 12 in which: the inclined axis ofsaid mixer drum and the axis of said drive sprocket are oriented at anangle to said frame support along its longitudinal axis and said rolleraxis comprises a pair of laterally spaced rollers supported by saidframe and engaging the under curved side of said mixeR drum in rollingcontact.
 14. A mounting for the power take-off-unit of a concrete readymix truck having a mixer drum rotatably mounted on the frame thereofbetween a front fixed bearing support and an inclined rear rollersupport, said power take-off-unit having a drive sprocket engaging adrive chain operatively engaging a driven sprocket in co-planarrelationship carried at one of the bearing supports of said mixer drumcomprising: means pivotally supporting said power unit from said framefor axial and angular movement of the drive sprocket along its axis;radially oriented arm means pivotally mounted for movement substantiallyin the plane of the axes of said sprockets, with one end thereofconnected to said frame substantially central of the axis of said drivensprocket and the other end thereof connected to an inner side of saidpower unit to maintain the radially spaced relationship between saidsprockets; anchor means universally connected at one end to the outerside of the power unit and at the other end to said frame allowing acircular moment of freedom to said power unit traversing the co-planarsprockets; roller means mounted upon said other end of said arm meansfor rotational idling contact with the rotating end of said mixer drum;and means biasing said power unit and drive sprocket about said pivotalsupport with said roller means maintained in said idling rotationalcontact whereby the co-planar relationship of said sprockets ismaintained irrespective of torsional and longitudinal displacements ofsaid frame and bearing supports for said mixer drum.
 15. A mounting fora power take-off-unit in accordance with claim 14 in which: the meanspivotally supporting said unit comprise a pair of linkages pivoted attheir respective ends upon vertically spaced parallel transverse axes,one of which extends substantially centrally of said unit and the otherof which is carried by said frame.
 16. A mounting for a powertake-off-unit in accordance with claim 14 in which: said radiallyoriented arm means includes a pair of threadably engaging rod membersadapted to be rotated in relation to each other and thereby adjust thetightness of said drive chain about said sprockets.
 17. A mounting for apower take-off-unit in accordance with claim 14 in which: said anchormeans includes a pair of threadably engaging rod members adapted to berotated in relation to each other and thereby adjust the loci of thecenter of said circular moment of freedom of said unit.